Bottom Line:
Breast cancer (BC) is one of the most common cancers in women, and it can often metastasize to the bone.In a previous study, we found the expression of matrix metalloproteinase 2 (MMP2) to be significantly more pronounced at metastatic bone sites than at orthotopic sites.MiR-106b levels in orthotopic tumor tissue showed a negative correlation with MMP2 expression and breast cancer bone metastasis.

fig01: Effects of matrix metalloproteinase 2 (MMP2) on migration and invasion of breast cancer (BC) cells. (a) The siRNA of MMP2 was transfected into SUM1315-bo. This was confirmed at both the gene and protein levels. Si-M1, si-M2, and si-M3 represent the three different siRNA pairs of MMP2. Si-M1 and si-M2 were used in all the subsequent experiments. (b) The invasiveness of MMP2 knockdown SUM1315-bo and the negative control (si-NC) cells were assessed using transwell assays. The invasiveness through 8 μm pore transwells was significantly lower in MMP2 knockdown SUM1315-bo than in the negative control (P < 0.05). Original magnification ×100. (c) The constructed expression vector pEGFP-C2-MMP2 was stably transfected into MCF-7, which was MMP2-negative. Transfection was confirmed at the protein level. (d) The invasiveness of MMP2 overexpressing MCF-7 (MCF7-MO) and the control cells were assessed by transwell assays. The invasiveness through 8 μm pore transwells was found to be significantly higher in MMP2 over-expressing MCF-7 than in controls (P < 0.05). Original magnification ×100.

Mentions:
The role of MMP2 on cell migration and invasion of SUM1315-bo cells was demonstrated by knocking down MMP2 using siRNA. We used SUM1315-bo cells because they have a high migratory potential and express endogenous MMP2 in large quantities. Three small interfering RNA (siRNA)-coding oligos against human MMP2 were designed and compared. The two most effective MMP2 siRNA (si-M1 and si-M2) constructs had target sequences of AGU AGA UCC AGU AUU CAU UCC CUG C (si-M1) and AGA AGU UGU AGU UGG CCA CAU CUG G (si-M2). These sequences were verified at the mRNA and protein levels (Fig.1a). Notably, silencing of MMP2 was found to be associated with significantly decreased invasive and migratory ability in SUM1315-bo cells (Fig.1b).

fig01: Effects of matrix metalloproteinase 2 (MMP2) on migration and invasion of breast cancer (BC) cells. (a) The siRNA of MMP2 was transfected into SUM1315-bo. This was confirmed at both the gene and protein levels. Si-M1, si-M2, and si-M3 represent the three different siRNA pairs of MMP2. Si-M1 and si-M2 were used in all the subsequent experiments. (b) The invasiveness of MMP2 knockdown SUM1315-bo and the negative control (si-NC) cells were assessed using transwell assays. The invasiveness through 8 μm pore transwells was significantly lower in MMP2 knockdown SUM1315-bo than in the negative control (P < 0.05). Original magnification ×100. (c) The constructed expression vector pEGFP-C2-MMP2 was stably transfected into MCF-7, which was MMP2-negative. Transfection was confirmed at the protein level. (d) The invasiveness of MMP2 overexpressing MCF-7 (MCF7-MO) and the control cells were assessed by transwell assays. The invasiveness through 8 μm pore transwells was found to be significantly higher in MMP2 over-expressing MCF-7 than in controls (P < 0.05). Original magnification ×100.

Mentions:
The role of MMP2 on cell migration and invasion of SUM1315-bo cells was demonstrated by knocking down MMP2 using siRNA. We used SUM1315-bo cells because they have a high migratory potential and express endogenous MMP2 in large quantities. Three small interfering RNA (siRNA)-coding oligos against human MMP2 were designed and compared. The two most effective MMP2 siRNA (si-M1 and si-M2) constructs had target sequences of AGU AGA UCC AGU AUU CAU UCC CUG C (si-M1) and AGA AGU UGU AGU UGG CCA CAU CUG G (si-M2). These sequences were verified at the mRNA and protein levels (Fig.1a). Notably, silencing of MMP2 was found to be associated with significantly decreased invasive and migratory ability in SUM1315-bo cells (Fig.1b).

Bottom Line:
Breast cancer (BC) is one of the most common cancers in women, and it can often metastasize to the bone.In a previous study, we found the expression of matrix metalloproteinase 2 (MMP2) to be significantly more pronounced at metastatic bone sites than at orthotopic sites.MiR-106b levels in orthotopic tumor tissue showed a negative correlation with MMP2 expression and breast cancer bone metastasis.